The present invention relates to a transmission apparatus for motor vehicle in which the engine is longitudinally mounted in the front position of the vehicle and output of the engine is transmitted to the front and selectively to the rear axle of the vehicle through the transmission. More particularly the present invention relates to a transmission apparatus which transmits the power of the engine both to the front axle and to four wheels of front and rear.
In recent years, the four-wheel driving passenger car has been preferably and widely used, because it has high steering stability. It is desirable that such a car can be economically driven at a high speed on the highway for example with a boat-trailer, camping trailer and the like, and on the other hand, can be powerfully driven on mountain path, on the sands, and the like.
Typical means for meeting such a requirement is to increase the changing speed stage of the transmission in number of the stage. However, this means results in complexity of manipulation for changing the speed of the transmission, thereby to decrease its practicability. In order to remove such disadvantages, it has been proposed to provide a sub-transmission together with the main transmission of which sub-transmission may be manipulated to change the transmission speed independent of the main transmission. If there is provided with a main transmission having four-speed-stage and a sub-transmission having two-speed-stage, the transmission having eight-speed-stage may be obtained. Namely, when the sub-transmission is set in the lower speed stage, the main transmission can transmit four speeds in the lower speed range, and when the sub-transmission is set in the higher speed stage, four speed in the higher speed range can be transmitted through the main transmission. In accordance with this sub-transmission apparatus, the manipulation is simply performed, because the main transmission may be manipulated in four stages. However, it is necessary to provide a special space in the transmission housing for the sub-transmission, which results in increase of the transmission in dimensions. Especially, since the above-mentioned transmission apparatus which can be manipulated to convert into four-wheel driving transmission is provided with clutch means for transmitting the power of the engine to the sub-drive wheels, the apparatus inherently has a long length. Therefore, such an apparatus is further increased in length by the sub-transmission.
In such a vehicle in which the engine is longitudinally mounted in the front position thereof, the engine must be extended forward from the front wheels more than conventional car because of the long size transmission or the transmission must be positioned rearward whereby the space for the driver in the vehicle is reduced. If the length from the front wheels to the front end of the car becomes long, it will become difficult to manipulate the steering wheel of the car.
Further, in the case that the sub-transmission is provided to transmit the output of the main transmission, the sub-transmission must be designed to have great dimensional size. If the inertia lock type synchromesh mechanism is employed in such a sub-transmission, inertia mass of the synchronized members in the mechanism will be great value, which makes the manipulation of the sub-transmission heavy.
Therefore, it is the object of the present invention to provide a transmission apparatus which need not a special space for the sub-transmission in the transmission housing, which may be manufactured in small size, and of which sub-transmission may be easily manipulated.